This invention relates to apparatus for cleaning semiconductor processing equipment and transporting same to a clean room environment and the method of conducting the cleaning and transport thereof.
In the manufacture of semiconductor components such as integrated circuits, the processing of the semiconductor substrate utilizes a number of deposition steps. Deposition of metallic materials occurs in a variety of environments and under different conditions. Common to virtually all deposition techniques is the buildup of deposited material on the processing equipment itself. Since the manufacturing yield depends on the deposition of material in certain carefully prescribed locations, the introduction of material in an unpredictable manner due to flaking and spalling from deposited material on the equipment itself is to be avoided. Consequently, the equipment is periodically disassembled into components and subjected to elaborate cleaning rituals. The cleaning process typically utilizes a number of steps designed to etch away deposited material. The cleaning process is carried out at a location other than the manufacturing environment.
The manner of transport of the equipment components to the cleaning process area is not particularly significant since the components will be acid-bathed, surfaced textured, and carefully washed under controlled conditions. The final washing and drying in an inert atmosphere are undertaken to provide a component having a surface free of contamination. The component is then packaged and sealed for return to the manufacturing environment.
Since the initial cleaning steps are concerned with the removal of deposited masses of material these steps are not well-suited to being performed in a clean room environment. The particles generated prevent maintaining the strict standards of atmospheric cleanliness associated with clean rooms having a low particle count per unit volume. However, the final preparation steps and packaging are carried out in a clean room environment, typically a class 100 room, wherein the quantity of airborne particles per unit volume is strictly controlled. The objective of the process is to return the equipment components to the manufacturing environment with a cleanliness factor that meets an objective standard so as not to reduce the manufacturing yield when returned to service.
Heretofore, it is customary to complete the physical removal of depositing materials in a processing environment and then place the equipment components in a water-filled wheeled carrier. The wheeled carrier serves as a holding tank as it is moved into the final packaging area. The transport of the carrier into the clean room has the capability of introducing contaminants into the final clean room. In this room, the equipment components are physically removed from the holding tank and wiped down with a lint-free cloth while exposed to the atmosphere. The wipe-down frequently adds particles to the component surface as well as leaving minute pieces of threads on the surface. Next, the components are dried in an oven having a nitrogen environment. Particles on the component surface after wipe-down tend to remain in place thereby degrading the effectiveness of the cleaning process.
The present invention is directed to apparatus which enables the equipment components to be introduced into the final clean room environment for final drying and packaging without introducing contaminants from the cleaning process environment. In addition, the apparatus provides immersion cleaning during transport to remove particles adhering to the surface which had their origin in the initial stages of cleaning. As a result, the delivery or transport vehicle with the contained liquid therein is eliminated and therefore does not introduce contaminants into the final clean room from the processing environment.
The present invention also comprises a method of immersion cleaning of the components during transport while submerged in liquid. The cleaning step takes place during the introduction of the component into the clean room. The cleaning liquid is shielded from the processing environment by a particle barrier to substantially reduce the opportunity for airborne particles to enter the liquid. A positive pressure gradient from the final clean room to the processing environment aids in reducing the opportunity for particles to enter the liquid.
Accordingly, the present invention is directed to the provision of apparatus for transporting equipment components from a processing environment that is characterized by a high particle containing atmosphere to a clean room having a controlled environment. The invention includes the method of effecting the transport of components while conducting immersion cleaning to further remove surface adhering particles from the components.